instmctions); The Mouse Behavioral Assessment and Breeding Core is an extension of a core in the previously supported program. The Core has a number of specific tasks that support all of the projects in the program. The specific tasks undertaken by the experienced Core staff are the following: a) behavioral assessment of wake and sleep stages in mice using high throughput video assessment of behavior. In the previous period of funding we developed a novel methodology to assess wake and stages of sleep from video analysis; 2) recording of wake and sleep using electroencephalogram and electromyogram. This involves implantation of electrodes and careful scoring of records. Core staff also perform spectral analysis of the EEG signal; 3) these studies generate a considerable amount of behavioral data. Thus, the Core also does data reduction and, using customized software we have developed, provides summary data to investigators in an easy to access format; 4) this new program of research now involves breeding and genotyping of a number of specific transgenic mice. It is proposed that this is best done by a central facility and therefore this Core now provides breeding of mice and genotyping. While these are ongoing and enhanced services that the Core will provide, the Core is also engaged in innovative activities. First, Core staff will conduct a study of changes in sleep/wake across the lifespan in C57BL/6NIA mice. These mice are used in Projects 01 and 02. Thus, these data will inform the science of these two projects. The Core is also addressing the capability to create new transgenic mice. As a first step, we proposed to create conditional transgenics where expression of Homer l a can be increased in older animals. This is an immediate future direction for Project 02. Finally, the Core will work to extend, in collaboration with staff in Core C, the video-based technology so that wake and stages of sleep can be assessed in individual mice among a group of mice that are raised together. RELEVANCE (See Instmctions): Mice are a powerful model system to study sleep and aging effects. Mice show the same changes in wake and sleep as humans. This Core provides the ability to study sleep and wake in mice of all ages to provide the behavioral assessments needed for this program of research. It also will create mutant mice that provide the capability to study mice with alteration in a particular gene and be responsible for mouse breeding.